I bought an Osprey pen with the Titanium Ultraflex nib.
There were three problems:
Firstly the ink went right up between the nib unit and the pink translucent body of the pen. It looked awful; this has never happened with other pens which I have.
Secondly,.There was no flex in the nib. None
Thirdly, the first ink I tried was a Graf Von Faber Castell. The ink literally ran out of the nib. I tried various other inks. The least awful was Iroshizuko Yama Budo. I wrote in a variety of papers but there was still so much ink flow that the ink soaked through the
Tamoe River Paper -I do mean soaked through,not showed through. Rhodia paper fared little better.
As you can imagine I am very, very disappointed. The pen is beautiful but not usable with this nib.
i have enjoyed this nib so much. my handwriting looks great and the flex is easy and effortless.
I had the opportunity to try all the sizes and finally got the medium one. In a short time, I tested it with some of my inks and here are my impressions so far:
1) J. Herbin Rouille D'Ancre
While this ink shades beautifully with this nib's impressive flex, it had pretty dry flow most of the time and I experienced some railroading.
2) Pilot Iroshizuku Fuyu-Gaki
As expected from an Iroshizuku ink, this one flows smoothly. Well, maybe a bit too smoothly. While there wasn't any railroading, I think this ink was actually too wet to be used in a flex nib like this with an ebonite feed. When used with no pressure, I had pretty thick lines with less precision where they were otherwise thin and precise. Still it is a lovely color and I haven't had any issues about bleeding when paired with Tomoe River 52gsm.
3) Parker Quink Black
This is my favourite so far! While it's not as wet as Fuyu-Gaki, this ink still flows well and I think this is the one that was able to catch a balance between too dry and too wet. There wasn't any railroading even when used in long sessions. Dries reasonably fast with a bronze sheen. Being classy and affordable to keep up with this "fountain" of a fountain pen -an ink drinking monster really-, this one was my favourite performer. Both on the paper and in the wallet.
As advertised. A very nice product.
The thick one is good, but the thin one is not very thin, so it's not very good. If this is the case, the G-pen unit would be better.